IceTop Internal Review Madison, November 3-4, 2010

1. IceTop Internal Review Madison, November 3-4, 2010 Physical Description of IceTop Paul Evenson, University of Delaware

2. Ice Cube Operation

3. The IceTop Square Kilometer Array • Will consist of 82 “stations” • One station located near each in-ice “string” plus two “infill” • Uses the same surface data cable as the string • Each station has two “tanks” separated by ten meters • Local coincidence between the tanks in the station reduces trigger rate • One low gain and one high gain DOM in each tank gives required dynamic range

4. Ice Top “Tanks” • Emulate natural growth of lake ice. • Produce clear ice by a method known in the materials industry as “zone refining” in which a crystal forming from the liquid phase excludes impurities, concentrating them in the remaining liquid. • In a lake, “impurities” (which include the oxygen fish need to survive) are diluted in the large volume of lake water under the ice. • Technical issues at Pole all derive from the need to conduct the freeze in and with a volume of water comparable to that of the end product.

5. IceTop Objective: Calibration • Determine size (i.e. estimate energy) of cosmic-ray showers with E0 > 300 TeV • Energy deposition of muon bundle in IceCube is correlated with E0 • IceTop direction gives tagged muon beam • SPASE-AMANDA proof of method

6. Incident cosmic-ray nucleus n Penetrating muon bundle in shower core IceTop Objective: EeV nm Detection via Shower Veto m Threshold ~ 1017 eV to veto this background This background for EeV events can be vetoed by detecting the fringe of the coincident horizontal air shower in an array of water Cherenkov detectors (cf. Ave et al., PRL 85 (2000) 2244, analysis of Haverah Park)

7. IceTop Objective: Cosmic Ray Composition • Coincident events: • Measure size at surface & energy deposition in deep detector • Primary energy and mass can be separately determined Signal in deep ice Signal in surface array

8. IceTop Capability: Heliospheric Physics • IceTop array will detect a million muons every ten seconds • Photons and electrons are also detected and to some extent can be resolved from muons • Statistical precision for observing solar and heliospheric phenomena will greatly exceed that of neutron monitors • Detailed analysis of IceTop signals will allow estimation of the top of atmosphere spectrum of primary protons in the 1-10 GeV energy range • The energy coverage of IceTop is complementary to that of a neutron monitor

9. Degassing System • Pump, filter, and contactor • Submerged in tank to eliminate most leaks • Only pump power and vacuum line emerge • They exit through the pressure relief tube

10. Production Line

11. Dig a Trench and Position Tanks

12. Fill Tanks with Water

13. Install the Sunshade • Metal frame with fabric surface • Open at the top • Opaque, with reflective white outer surface and black inner surface

14. Preparing to Close Tank • Dual degassing units are seen under 75 cm of ice • DOMs are frozen into the ice

15. Tank Closeout

16. Backfill Tank with m telescope

17. Key IceTop Parameters Are Maintained Online • Configuration: • http://wiki.icecube.wisc.edu/index.php/IceTop_Configurations • Geometry: • http://wiki.icecube.wisc.edu/index.php/IceTop_Tank_Geometry

18. Configuration Example

19. Geometry Example(Page Top)

20. Geometry Example Continued